Jump-spark indicator.



N0. 851,751. PATENTED APRl 30, 1907. 0. C. HOFFMANN.

JUMP SPARK INDICATOR.

APPLIOATION FILED MA311, 1905.

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UNITED srarns PArnNr orrrcn.

OTTO C. HOFFMANN, OF BUFFALO, NEW YORK, ASSIGNOR TO CHICAGO FUSE WIRE AND MANUFACTURING COMPANY, OF CHICAGO, ILLINOIS.

JUMP-SPARK INDICATOR.

Specification of Letters Patent.

.Patented April 3o, 1907.-

Application filed March 21,1905. Serial No. 251,333.

Vwhich may be taken alone or associated with other devices. When so associated I prefer to employ it in connection with some device for opening electric circuits, such as switches, electric fuses, etc. lWhen employed with fuses it has especial bearing on an adaptability to the class known as inclosed fuses.

viliary fuse or indicator fuse.

inasmuch as it may be employed to indicate whether the fuse has been blown or is intact, this may be accomplished in two ways.

" First, by the spark itself, and secondly, by

furnishing in connection with the spark some means for recording the fact that it has passed, such as the discoloration of specially repared or chemicalized paper, mica, etc. When-,applied to inclosed fuses the jump sparkindicator has been found to possess great advantages over any other known type, and .especially advantages over the aux- T he use of the auxiliary indicator fuse has been found to disturb the calibration of the fuse itselfto a more or less extent. Under conditions of the presen day .demand and specification forinclose fuses, the current carrying capacity and the blowing point, under different time limits, has been brought to such a degree of exactitude that every disturbing factor must be-avoided to secure anything approaching the desired accuracy. The auxiliary indicating fuse consists of the small wire attached to the terminals of the fuse which constantly carries more or less of the current. It always stands attached to the two fuse terminals in shunt of the fuse and the current arriving. at the terminals obeys Ohms law, a greater or less quantity always being carried by the auxiliary fuse; this is subject to accident of manufacturing and is never found twice alike; furthermore the auxiliary fuse changes in temperature; it is found to vary with the relative temperature, inasmuch as the latter is at or near the surface of the inclosing envelop or casing of the fuse. All these difliculties are avoided if an indicator can be secured which is not closed as to circuit, and therefore, does not shunt any of the current away from the fuse itself, and thereby avoiding all disturbanceof the calibration of the main fuse. This most desirable end has at last been attained by the employment of the present jump spark indicator, which is an open circuited arrangement, and by means of which no current is shunted away from the main fuse, nor no current carried over any p ath except the main fuse until 'after the main fuse has not only been ruptured, but after the arc has been absorbed 'or extinguished and the path practically opened. Whereupon the onrushing current leaps the spark gap orgaps; this is due to the electromotive force of rupture or discharge from the inductance, such as it may be, of the circuit as a whole, or of such portieri of it asi may be included within the branch of the circuit controlled by the fuse; all of which is well understood in the art, and it is a well known fact that the momentary electromotive force at such a time, rises to values far in excess of the normal difference of potentials at the terminals of the fuse, and in some instances may arise far in excess of the maximum electromotive force of the distribution system to `which the fuse may be connected. And it is this rise in electromotive force that is utilized for the purposes of breaking down the di-electric eaping the gap and causing the spark to pass. This once accomplished it becomes an easy matter to devise some means, such as paper or other suitable material which may be or become chemicalized, etc. for recording the passage of such spark and thereby obtaining a visual indication and record of the opera tion. It being known that this operation could never take place without the main fuse first having been open circuited, it becomes, therefore, a-most faithful indicator of the condition of the fuse or other circuit opening device with which it is organized to co-operate.

The invention may be embodied in a number of forms. A sufficient illustration, however, is given in the drawings for complete understanding of one embodiment thereof, which may be described as follows:

Figure 1 represents a general diagrammatic representation of a system of distribu- IOO IIO

ICI

` consisting of two terminals a and a.

tion oi electrical supply with the jump sparkv indicators in position. Fig. 2 is a longitudinal section of inclosed fuse with jump spark indicator in" position. Fig. 3 is enlarged view of one of the wallsof an inclosed lise with an alternate form ol tor. Fig. ^i is a diagrammatic view olfr an alternate form. Figs. 5 and 6 aredetails.

n Fig. l illustrates an electric circuit with the generator G circuit-mains g 'and g', circuit opening means such as switch S and inclosed use F, each of which are shown as being supplied with a jump spark device A shownl1 s e fuse F is shown as mounted upon a fuse base of usual construction and connected in circuit with the service or translating devices T.

In Fig. 2 is illustrated an inclosed fuse F made up of the caps OO and the shell B and the fuse F. A depression in the outer wall of the shell ofthe fuse is shown at B in which is located the jump spark device A consisting of the terminals a and a!l over all of which is located asuitable cover Dwhich may or may not be transparent. This cover D may be translucentor-it may consist of a film or sheet so organized as to change its color on vthe passage 'of electric spark at A. The terminals a and a run .along-on or within a-casing in which they make suitable connection to terminals OC.

The alternate form shown in Fig. 3 relates simply to` detail of structure of the indicator which here instead of consistingin a single air gap at A, consists of a plurality oi air gaps located between conducting particles P, such for instance,.as Carbon, iron cr suitable material which may be sprinkled and caused to adhere upon the surface of a non-conductor and in contact with which the twoterminals a2 and a3 are connected. The surface E may be chemicalized or otherwise render the passage of the spark between the particles P visible, or recordisuch passage in any visible manner, and this again may receive a covering; transparent or translucent, such as mica H, and .the whole may be protected by a label having an aperture or otherwise provided for inspection of the jump spark device or the result of its operation which, is indicated at. I; also may be seen in Fig. 6, the'aperture if 'any being indicated by I It will readily be understood that-the particles themselvesmay'be of such character.

as to be. changed chemically by the passage of`the s ark or the cooperation between them-and thel paper E may besuch that/a visual indication of the character named may ad. i

vention may take on many different characteristics and any form of jumps ark apparatus, or any character of materia which will i'ullil the conditionsherein named may be used and associated with any forrnofcircuit jump spark indica l It will be readily understood thatlthein- I starei v ycarrying the present invention into eilect,

l would state cover D may be omitted or it mica, andthe preparedpaper 4or surface E may consist of paper wetted with ammonium sulfate solution and dried before being used.

Having thus fully described the the invention and the method .of its operation, whatwe claim and desire to secure by Letters Patent is:

1. "in combination with a ynon-inductive electric conductor, terminals for such conductor, and a jump sparkdevice located in shunt of such conductor, and means associated with the jumpspark device for visuallyindicating the passage of the spark.

2. A fuse for an electric circuit, and a eparkv gap lindicator connected inshunt to the use.

3., An inclosed fuse having terminals and a jump spark device in shunt'with said terminals, and means for recordingthe passage of the spark exterior to the inclosing envelop of the fuse'. 4. In an inclosed fuse, terminals for the fuse and a inclosing envelop in shunt circuit in relation may consist ol' i with the terminals and a shield forthe device.

j 5. In an inclosed fuse, a terminal for a fuse, a jump spark device in contact with the terminal, and a part chemically affected bythe spark acting at .the same time as a shield for the device.

6. ,ln an inclosed fuse a terminal for the fuse, a jump spark device in contact with the terminal and a double shield for the device, one of such shields consisting of; a transparent substancef 7. n an inclosed fuse a terminal for the fuse, a casing for the fuse, a depression in the Case, a jump spark device in contact with the .terminal located in the depression in the casing.4

8. In an inclosed fuse a terminal for the fuse a casingor the fuse, a depression in the case, a jump spark device in contact with the terminal located in the depression in the casductor, and means exterior to said case for indicating the passage of current through said auxiliary conductor.

In testimony whereofl have hereunto set my hand in presence of two subscribing witnesses. 4

. OTTO C. HOFFMANN.

Witnessesl.

' WILLIAMv H. CROSBY ARTHUR D. DONA] particles g the nature ciy jump 'spark device exterior to the.

case and connected to said main conllO 

